Oxidation process



Patented May 28, 1935 PATENT OFFICE OXIDATION PROCESS Frank A. Canon, New Brunswick, N. J., assignor to E. I. du Pont de Nemours and Company, Inc., Wilmington, DeL, a corporation of Delaware No Drawing.

Claims.

This invention relates to improved methods for oxidizing organic and inorganic compounds, and more particularly refers to the use of suspensions of manganese-dioxide produced according to the following instructions in oxidation processes.

It is well known that various compounds may be oxidized by the use of manganese-dioxide or ores containing manganese-dioxide. Large deposits of manganese-dioxide-.:ontaining ores have been discovered in many countries. However the great majority of these ore deposits are not suitable for use in numerous oxidation processes. The ore which has been found. to be particularly adapted to these processes is that obtained from Caucasia, commonly referred to as Lavino-Caucasian. Due to the great demand for this product and the expense of transportation it commands a premium in the market and in some instances sells for more than twice as much as pyrolusite ore from other sources. Despite this increased cost many industries prefer to use such ore in their oxidation processes because of its considerably greater efiiciency.

It is an object of the present invention to adapt manganese-dioxide-containing ores for use in various processes wherein they were formerly unsuited and in general to increase the efficiency of all pyrolusite ores. A further object is to utilize the vast deposits of ore which were formerly of little or no use due totheir low efficiency in oxidation processes. A still further object is to treat these cheap ores in a manner which will greatly enhance their oxidizing abilities. An additional object is to obtain these ores in such form that they possess a power of oxidation equal to or superior to the oxidizing power of expensive La-vino- Caucasian ore processed according to the prior art. Additional objects will become apparent from a consideration of the following description.

These objects are attained according to the herein described invention which in its preferred embodiment comprises wet-grinding a manganese-dioxide-containing ore and using the emulsion or suspension thereby obtained in the oxidation process.

The invention may be more readily understood by a consideration of the following illustrative examples, in which the quantities are stated in parts by weight.

Example 1 African pyrolusite containing 84-83% manganese-dioxide was wet-ground, and the resulting suspension or emulsion was used in the production of hydroquinone from sulfanilicacid. 1.05

Application December 1, 1933, Serial No. 700,623

pounds of crude hydroquinone were obtained per pound of aniline.

The same are was dry-ground according to the prior art so that 90% would pass through a 200 mesh screen. The resulting product was then substituted for the emulsion in the aforementioned process. In this case only 0.9 pound of crude hydroquinone were produced per pound of aniline. In other words, the oxidizing power of the emulsion was more than greater than the oxidizing power of manganese-dioxide processed according to customary methods.

Example 2 Example 3 Lavino-Caucasian ore containing 88.1% of manganese-dioxide, and generally conceded to be the best ore obtainable, was dry-ground so that 90% would pass through a 200 mesh screen. The ground product was used in the oxidation of sulfanilic acid, and resulted in a yield of 1.05 pounds of crude hydroquinone per pound of aniline.

8 mesh Virginia, ore containing 65.4% manganese-dioxide was wet-ground, and the resulting emulsion substituted for the dry-ground Lavino- Caucasian ore in the aforementioned process. Basing the result on the amount of manganesedioxide contained in the Virginia ore it was found that 78.5 pounds of manganese-dioxide contained in such ore would produce the same amount of hydroquinone from aniline as 88.1 pounds of manganese-dioxide contained in the Lavino- Caucasian ore.

Example 4 Virginia ore containing 75% manganesedioxide was wet-ground and the resulting emulsion used in the production of hydroquinone according to the directions contained in the aforementioned examples. 1.04 pounds of pure hydroquinone were obtained per pound of anil ne.

An amount of manganese-dioxide in emulsion form equivalent to that used above was first dried and then substituted in place of the above emulsion. The yield here was 1.02 pounds of pure hydroquinone per pound of aniline.

Example 5 When Lavino-Caucasian ore was wet-ground and the resulting emulsion used in the production of hydroquino-ne it was found that the amount of ore required was almost less than when ore processed according to the prior art was used.

The aforementioned results were checked by numerous experiments, and the same advantage Was observed in each case where the manganesedioxide was used in emulsion form.

It is to be understood that the aforementioned examples are illustrative merely of the methods of applying the process of the present invention, and are not intended as a limitation thereon. This invention is also applicable to other processes for the oxidation of inorganic or organic compounds wherein manganese-dioxide was formerly used. Among the numerous processes which fall within this category mention may be made of the oxidation of benzanthrone to dioxydibenzanthrone as well as the production of complex arsenic-containing compounds.

When reference is made in the present specification and claims to wet-grinding it is to be understood that this includes grinding in other media than water- For example the pyrolusite may be ground in sulfuric acid, or any liquid capable of forming a suspension or emulsion with the resulting particles. Grinding in water is usual- 1y preferable, since it is somewhat more rapid than grinding in a more viscous medium, and the equipment is not subjected to such a high rate of corrosion. The extent to which this wetgrinding may be carried is subject to considerable variation. Material ground so that it will pass through a 300 mesh screen is ordinarily preferred, although the size of the particles may be considerably larger or smaller than 300 mesh without departing from the scope of this invention.

While it is not intended to limit the present invention to any particular theory, nevertheless, it is believed that the individual particles of manganese-dioxide when wet-ground and used in emulsion form are rendered much more active than if they were used in the dry form according to well known processes. This activation may possibly be due to the presence of charges of electricity on the various particles, although such theory is advanced merely as a possible explanation of the resulting advantageous features. Regardless of the reason for this surprising phenomenon it is clear that the substitution of the emulsions described herein for the powders used in the prior art is exceedingly advantageous.

This invention permits the utilization of enormous quantities of manganese-dioxide-containing ores which were formerly ill-adapted for use in oxidation processes. It permits cheap ores to be used in order to obtain results which are equal to and in many cases even superior to the results obtained from the most expensive ore used according to well known methods, and likewise it greatly increases the efficiency of even the most expensive ores. Furthermore, it is obvious that a process using suspensions or emulsions is much more desirable from a commercial standpoint than one depending upon the use of powders, since emulsions may be readily pumped from one portion of the plant to another, whereas powders can only be handled with great difiiculty.

As many apparently widely diiferent embodiments or" this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

I claim:

1. An oxidation process which comprises treating the compounds to be oxidized with a suspension of wet-ground manganese-dioxide-containing material.

2. An organic oxidation process which comprises treating the organic compounds to be oxidized with a suspension of wet-ground manganese-dioxide-containing material.

3. In the oxidation of organic compounds by treatment with manganese-dioxide the step which comprises substituting an emulsion of wetground manganese-dioxide for the dry-ground 1nanganese-dioxide previously used.

4. In the production of hydroquinone by oxidizing a para-substituted phenol or amino-benzene with manganese-dioxide the step which comprises substituting an emulsion of wetground manganese-dioxide for the dry-ground manganese-dioxide previously used.

5. In the production of hydroquinone by oxidizing sulfa-nilic acid with manganese-dioxide the step which comprises substituting an emulsion of wet-ground manganese-dioxide for the dryground manganese-dioxide previously used.

FRANK A. CANON. 

